Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 021854

Area Forecast Discussion
National Weather Service Gaylord MI
154 PM EST Fri Dec 2 2016

Issued at 1023 AM EST Fri Dec 2 2016

Pesky stacked low pressure system over western Quebec is slowly
filling and slipping eastward. One more short wave trough and
thicker enhanced cloud cover, producing some light precip in
eastern upper and the tip of the mitt. Also some residual light
lake effect showers still ongoing over NW lower Michigan. But,
lake effect organization and intensities have really diminished
over the last several hours thanks to the development of a stout
temp inversion around 825 MB per this mornings 12Z sounding (KAPX
radar really shows some definitive transverse banding with the
lake effect returns...a telltale sign of convection hitting a cap

Rest of today: Minor precip anticipated. Short wave trough will
continue to sag through the afternoon followed by drier air/modest
low-mid level ridging nudging into the region heading into the
evening. So, some light lake effect, some light synoptic precip
through the afternoon, still a bit mixy or just changing to all
liquid as temps eventually warm to the middle and upper 30s.


.NEAR TERM...(Today and tonight)
Issued at 229 AM EST Fri Dec 2 2016

...Mixed rain and snow showers to continue...

High Impact Weather Potential: None

Pattern Synopsis/Forecast: Cool cyclonic flow continues across the
area at this early hour on backside of slowly departing Quebec low.
Lake processes continue in a marginally unstable environment,
although earlier departure of synoptic support has resulted in a
noticeable downtick in shower intensity and coverage across
northwest lower Michigan. Next wave/area of enhanced deep moisture
already rotating south into upper Michigan, with an associated
uptick in lake processes on Lake Superior. Precipitation type has
remained largely determined by elevation and distance from the
lakes, with mostly snow (minimal accumulations) across interior
regions, and mainly rain closer to the coasts.

Pattern will remain a slowly evolving one today through tonight,
with core of troughing gradually rotating off to the east. Cool low
level moisture rich flow will remain, although departure of already
marginal synoptic support will bring an ever shrinking convective

Primary Forecast Concerns: Addressing lingering lake induced rain
and snow showers.

Details: Band of enhanced moisture will rotate southeast across
northern lower Michigan this morning, likely providing a brief
uptick in west/northwest flow lake activity in the process. Core of
coldest h8 temperatures rotates south of the region this morning,
with actually some weak waa occurring in this layer from the north.
Combine that with a well advertised lowering of the convective
boundary layer, and lake induced instability slowly wanes through
the day into this evening. In fact, the vast majority of model
derived soundings show, even with somewhat favorable over-water
delta t`s, cloud top temperatures fail to reach -10c by this
afternoon and evening. This would suggest more of a drizzle scenario
in northwest flow lake activity. Still believe guidance may be a
touch aggressive lowering this inversion, expecting lake convection
to modify the lower levels more than progs would suggest. Upshot to
the above, still feel light showers are likely in those favored lake
effect areas, with overall precipitation amounts remaining very
light. This trend will continue tonight, with a continued slow
downtick in shower intensity. Precipitation type will be largely
predicated by elevation and shower intensity. A slowly warming
boundary layer does suggest more of a rain/snow scenario across
interior regions by later this morning and afternoon, with precip
largely remaining liquid near those big waters. May see some slushy
snow accumulations (well under an inch) this morning in the
highlands, with perhaps a dusting of snow again tonight. Not a big
deal for sure.

Expect mainly dry conditions away from the lake zones, although with
plenty of lingering cloud cover.


.SHORT TERM...(Saturday through Sunday night)
Issued at 229 AM EST Fri Dec 2 2016

...Lingering lake effect Saturday; More widespread precip arrives

High Impact Weather Potential: An inch or two of snow
possible Sunday afternoon-Sunday night.

Pattern Forecast: A 150 kt jet streak is expected to be nosing into
the Pac NW come Saturday morning with a large buckle in the jet
stream and associated closed upper level low evident across the
desert southwest. Low pressure that`s plagued northern Michigan
over the last 24 hours will be well off the East Coast with surface
high pressure overhead. As a result, cyclonic flow currently present
across the Great Lakes will transition to more zonal flow before
winds back southwesterly with return flow expected to prevail
Saturday night into Sunday ahead of a wave set to cross the region
Sunday afternoon-night.

Primary Forecast Concerns:

Several forecast challenges evident through the weekend with the
first ongoing at the start of the period. Despite a lack of any
lingering deeper moisture on Saturday, expecting light lake effect
showers to be ongoing across portions of NW Lower and eastern Upper
thanks to delta t`s approaching -16 C. Aformentioned lack of deep
moisture, especially above the -10 C isotherm, virtually no synoptic
support, and anemic inversion heights should limit the overall
coverage and intensity of showers throughout the day. In terms of p-
type, would expect the day to start as mainly snow showers with a
rain/snow mix becoming predominant by midday (higher terrain should
stay mainly snow). Winds begin to back southwesterly during the
afternoon and into the evening, gradually shifting lake induced
scattered shower chances northward as well.

Perhaps a slightly more impactful system arrives Sunday afternoon-
night as a northern stream disturbance and southern stream wave
phase over the mid-MS Valley and shift eastward across the Great
Lakes. Expecting precip to arrive from southwest to northeast Sunday
afternoon, also coinciding with the best pocket of forcing aloft.
Wouldn`t be shocked to see precip begin as a rain/snow mix before
transitioning to all snow during the late afternoon/early evening
hours. There continues to be quite a spread in raw QPF output
between guidance members between 12z Sun - 12z Mon, ranging from
0.05 - 0.20 inches. Several ensemble members including those from
the GEFS/SREF would suggest the lower end of that range prevails.
All in all, an inch or two of accumulation looks possible, so while
not necessarily impactful snow amounts, it`s expected to be the most
widespread wintry event in two weeks or so with some slick travel
possible as temps drop below freezing after sunset Sunday evening.

.LONG TERM...(Monday through Thursday)
Issued at 229 AM EST Fri Dec 2 2016

An active winter weather pattern will develop later next week as a
large plume of cold air breaks off from the Arctic circulation and
surges into the Northern Plains, moderating a bit by the time it
wobbles into the Great Lakes region. High pressure is expected to
provide a brief respite from precipitation Monday afternoon into
early Tuesday. Meanwhile, deepening low pressure traveling from the
Gulf Coast into the Ohio Valley will interact with a broad upper
trough Tuesday into Tuesday night to bring the potential for some
accumulating snowfall to northern Michigan.

The GFS and ECMWF both show the lake effect snow machine kicking in
the latter half of next week as persistent northwesterly low level
flow develops in conjunction with plummeting 850 mb temperatures.
Another significant system is progged to travel through the Ohio
Valley Wednesday night into Thursday, though the GFS and ECMWF
differ substantially in regards to its timing, dynamics, and track.
Regardless, the present track of this system would be favorable for
perhaps several inches of snow accumulation across northern
Michigan, especially in areas that see ongoing lake enhancement from
lakes Michigan and Superior. Winds will increase with this system on
Thursday with gusts to 30 mph possible.

Temperatures for the long term period will start out above normal
with highs in the upper 30s to low 40s. However, they will take a
quick downward turn for the second half of the week with highs by
Thursday only in the upper 20s to mid 30s.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 154 PM EST Fri Dec 2 2016

Solid MVFR cloud cover stretches from the Great Lakes back through
the northern plains, and will be with us for a large part of the
weekend. Some lingering light lake effect precip will impact TVC
through Saturday, although impact should be minimal.


Issued at 229 AM EST Fri Dec 2 2016

Gusty SCA producing northwest winds will continue today on
all waters, likely continuing into this evening across northern Lake
Huron. Winds will diminish overnight, with light winds expected
Saturday into Saturday night.


LH...SMALL CRAFT ADVISORY until 11 PM EST this evening for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 7 PM EST this evening for LMZ323-341-
LS...SMALL CRAFT ADVISORY until 7 PM EST this evening for LSZ321-322.


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